Occlusion Detection via Perturbed Force Response Analysis
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Solution Overview
Problem
Existing fluid delivery systems, particularly those used in extracorporeal blood treatment, face challenges in detecting occlusions at low infusion flow rates and accommodating variability in syringe characteristics and operating conditions, leading to delayed detection of infusion abnormalities.
Innovation Solution
The system employs a normalized area ratio based on measured maximum perturbation force to detect occlusions, using a force transducer and controller to intermittently perturb fluid flow and measure perturbed force responses, allowing for early detection of occlusions even at low flow rates and varying system configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional continuous pressure monitoring is used, then occlusions can be detected, but detection is delayed at low flow rates and cannot accommodate syringe variability
Solution Approach 1:
The system applies periodic perturbations to the fluid flow by intermittently advancing the syringe plunger by small increments (e.g., 0.01-0.1 mL) rather than continuous monitoring. This periodic action creates measurable pressure waves that propagate through the infusion line, allowing detection of occlusions through analysis of the perturbation response characteristics, achieving timely detection even at low flow rates
Solution Approach 2:
The system changes the flow rate parameter dynamically by applying small step changes (perturbations) to the infusion flow. By measuring the pressure response to these controlled parameter changes and analyzing characteristics such as the area under the pressure-time curve, the system can detect occlusions while accommodating variability in syringe characteristics and operating conditions
2Object-affected harmful factors
If low infusion flow rates are used, then patient safety is improved, but occlusion detection becomes more difficult and delayed
Solution Approach 1:
By applying periodic perturbations to the low flow rate infusion, the system creates detectable pressure signals that propagate through the infusion line. The perturbation response analysis allows occlusion detection even when the base flow rate is low, maintaining patient safety while enabling timely detection of abnormalities
Solution Approach 2:
The system introduces mechanical disturbances (perturbations) to the fluid flow by intermittently advancing the plunger. These mechanical vibrations create pressure waves that can be detected and analyzed to identify occlusions, making detection feasible even at low infusion flow rates where conventional monitoring struggles
3Adaptability or versatility
If syringe characteristics and operating conditions vary, then system adaptability is improved, but detection accuracy becomes inconsistent
Solution Approach 1:
The system measures the pressure response to perturbations and uses this feedback to detect occlusions. By analyzing the area under the pressure-time curve and comparing it to expected values, the system can accommodate variability in syringe characteristics and operating conditions while maintaining consistent detection accuracy through adaptive thresholding and normalization techniques
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables timely detection of occlusions and insufficient infusion flows, reducing the risk of blood clots by signaling occlusions promptly, even in systems with complex characteristics and low flow rates, thus enhancing patient safety.
Implementation Method 1
a force transducer configured to measure a perturbed force response over time resulting from each of the one or more perturbations
Data Source
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AI summary
A system, method or apparatus to detect abnormalities in delivery of a fluid may include an infusion apparatus that is controllable to cause one or more perturbations in a fluid flow (e.g., each of the one or more perturbations in the fluid flow may result in a measurable perturbed force response). A force signal representative of the perturbed force response may be used to determine an integrated perturbed force response value (e.g., using integration of the force signal over a perturbation time period; the integrated perturbed force response value being representative of an additional force caused by the at least one perturbation over an equilibrium force). A ratio between the integrated perturbed force response value and a normalizing value (e.g., based at least on a maximum perturbation force of the perturbed force response) may be used to determine if fluid flow is occluded.